Arty Z7 manual jtag through F2232HQ

[davidv1992]

I am trying to manually get the ftdi f2232hq jtag working on the arty z7. However, when driving the TMS, TDI and CLK lines through libftdi the TDO pin seems to remain stuck in a high state, even when trying to read/write the instruction registers.

I have read that for some of the other digilent boards (particularly the cmod a7, see discussion in https://forum.digilent.com/topic/5395-cmod-a7-standard-ftdi-jtag-access-not-working/) that they require pulling specific other pins high or low (ADBUS7 high for the CMOD-a7) on that specific interface. I have tried ADBUS7 but that didn't seem to do anything for the arty z7, what am I missing?

Unfortunately, the specific details around the f2232hq seem to be missing from the schematics, but perhaps at least the information on which pins need to be pulled high/low could be shared?

[JColvin]

Hi @davidv1992,

I asked the engineer who originally gave Jon his information way back in the day on the Cmod A7 thread about your question and got the following response:

Quote

ADBUS7 is connected to the OE pin of the tri-state buffers that are between the USB controller and the JTAG nets of the rest of the board. It needs to be driven to a '1' to enable those buffers

As for the missing schematic page, that is an intentional decision made by Digilent (you can read a discussion about it in this thread here: https://forum.digilent.com/topic/20362-usb-proguart-schematic-request/)

Let me know if you have any questions.

Thanks,
JColvin

 

[davidv1992]

Thanks for the information,

Tried the ADBUS7 pin again and this time it worked. Guess i must have missed one of the direction bits last time.